Performance Test on Diesel Engine

LOAD TEST ON DIESEL ENGINE Ex. No :

Date :

Aim : To conduct load test on given diesel engine in order to determine: 1. Brake power of the engine 2. Indicated power of the engine 3. Total fuel consumption 4. Specific fuel consumption 5. Mechanical efficiency 6. Break thermal efficiency or overall efficiency 7. Indicated thermal efficiency

Apparatus Required : 1. 2. 3. 4.

Diesel engine with loading arrangement Thread and scale (or) measuring tape Stop watch Tachometer

Theory and Description : In diesel engine the diesel is used as the fuel . The diesel engine may be either two stroke engine or four stroke engine . In two stroke engine there is a one power stroke for each revolution of the crank shaft . In four stroke engine there is a one power stroke for every two revolution of the crank shaft , Most of the heavy duty engines are four stroke engines . The engine is provided with suitable loading arrangement to apple and measure the load . The provisions are also available to measure the fuel consumption and speed . Definitions : Break power : The useful power available at the crank shaft of the engine is called brake power (BP ) . The brake power of the engine are determined by 1. Rope brake dynamometer ( T = WRe ) and BP = 2𝜋 NT KW 2. Prony brake dynamometer (T = WL ) and 60 x 1000 3. Hydraulic dynamometer BP = WN / C Kw 4. Electrical dynamometer

Indicated power : The power actually developed inside the cylinder due to the combustion of fuel are called indicated power (IP) (or) IP = F.P + B.P where F.P = Frictional Power

Specific Fuel Consumption : It is defined as the mass of the fuel consumed per hour per brake power of the engine . Its unit is Kg / KW – hr SFC = TFC B.P Where TFC = Total Fuel consumption in kg / hr

Total Fuel Consumption : It is the mass of fuel consumed at particular load consumed at particular load per hour .It is expressed in kg / hr

Mechanical Efficiency : It is defined as the ratio of Brake power to indicated power

mech

= ___B.P Heat Supplied

x 100

Brake thermal efficiency or overall efficiency : It is defined as the ratio of brake power to heat supplied by the combustion of fuel .

B.T

or

overall

=

B.P Heat Supplied

Heat supplied = mass of the fuel consumed per sec x calorific value of fuel = mf x C.V. mf

= TFC Kg 3600 sec The calorific value of the diesel ranges from 42,000 KJ / Kg to 45,000 KJ/Kg depends on the quality of the fuel . The calorific value of petrol ranges from 41000 KJ/Kg to 44000 KJ/Kg

Indicated thermal efficiency or Thermal efficiency It is defined as the ratio of indicated power to heat supplied by the combustion of fuel

I.T

=

I.P Heat supplied

=

I.P mf x C.V

x 100

x 100 ;

mf = TFC kg/sec 3600

Procedure : 1. From the name plate details calculate the maximum load that can be applied on the given engine. 2. Check the engine for fuel availability , lubricant and cooling water connection. 3. Release the load on the engine and start the engine with no load condition . Allow the engine to run for few minute to attain rated speed 4. Note the speed of the engine and time taken for consumption of 10 cc of fuel 5. Increase the load on the engine and note the speed of the engine and time taken for 10cc of fuel consumption 6. Repeat the procedure ‘5’ up to 75% of the maximum load and tabulate the readings.

Graph : The following graphs has to be drawn 1. B.P Vs TFC 2. B.P Vs SFC 3. B.P Vs mech 4. B.P Vs B.T 5. B.P Vs I.T

Results :

Load test on given diesel engine were conducted and the TFC ,BP , IP , SFC ,

B.T

and

I.T

were determined at different loads .

mech,